Stung by Lalu Prasad's snide remarks describing him as a 'weather man', Union Minister Ram Vilas Paswan today hit back at the RJD supremo asking him to explain his alliance with his bitter foe-turned-friend Nitish Kumar.

"Instead of calling me a 'weather man', Prasad should explain as to why he had to join forces with senior JD(U) leader Nitish Kumar whom he had been denouncing with choicest words for past 20 years," he told reporters here.

His remarks came after Prasad dubbed him as a "weather man", accusing him of "changing tack to suit his own political requirements without carrying a baggage of ideology".

At a rally in Chapra addressed earlier in the day by RJD, JD(U) and Congress for an Assembly bye-election, Prasad said, "He (Paswan) is a rank opportunist who switches sides at the drop of a hat."